沿海双向声传播测流研究与实验

Study and field experiment of reciprocal sound transmission for current measurement in the coastal sea

2009年3月10-11日,用沿海声层析仪在我国台州大陈岛近海进行了一次双方向声传播测流实验。采用5 kHz的10阶M序列信号,利用GPS时钟进行异地时间同步,完成了水下信号的发射和接收,实现了双向声传播时间的精确测量。2个声传播站位间距为11km,实验历时26h。与此同时,在2个声传播站位间还进行了6次温度、盐度和流速的断面走行观测。2个站接收到的信号的信噪比达到了180以上,由双向声传播时间差得到的测线间的平均流速显示了典型的半日潮的变化。声传播观测所得的平均流速与声学多普勒流速剖面仪(ADCP)断面走行观测结果基本一致,两者之差的平均值为0.04m/s。

A reciprocal sound transmission experiment for current measurement was carried out on the two days of March 10, 11, 2009 in the region near the Daehen Island of Taizhou City, China, using the coastal acoustic tomography system （CATS）. The reciprocal acoustic travel time between the two separated stations was measured by using a 5 kHz carrier modulated with the M-sequence of 10th order and a GPS clock. The distance between the two stations was about llkm, and the duration of the experiment was about 26 hours. During the sound transmission experiment, the 6 repeat shipboard acoustic doppler current profile （ADCP） survey and the conductivity-temperature-depth （CTD） survey were also carried out to measure the current velocity, temperature and salinity fields for comparing with the sound transmission results. The signal to noise ratio of the received signal obtained at two stations, reached about 180, and the range-averaged current velocities derived from the difference of reciprocal travel time showed a typical semidiumal tide variation, and were in good agreement with the along sectional mean velocity obtained by the ADCP. The differentee of the mean velocity between sound transmission results and ADCP is 0.04m/s.